Attachment for lenses.



' Witness F. H. WILLIAMS.

ATTACHMENT FOB LENSES.

APPLIOATIOI TILED APR. 21, 1909.

Patented Apr. 5, 1910. 6 d

FRANK ULRIC WILLIAMS, 0F CARTHAGE, MISSOURI.

ATTACHMENT FOR LENSES.

Specification of Letters Patent.

Patented Apr. 5, 1910.

Application filed April 21, 1909. Serial No. 491,252.

0 all whom it may concern:

Be it known that I, FRANK ULRIG WIL- LI'AMS, a citizen of the UnitedStates, re siding at Carthage, in the county of Jasper and State ofMissouri, have invented a new and useful Attachment for Lenses, of whichthe following is a specification.

This invention has reference to improvements in attachments for lensesand is designed more especially for use in connection with projectionlenses whereby a lens constructed to produce a certain size picture upona screen at a certain distance therefrom may be made to produce upon thescreen ictures of other sizes without changing the distance of the lensfrom the screen, or may be made to produce pictures of the same sizeupon the screen at varying distances therefrom.

Projection lenses are usually made in several sizes capable of producingthe same size picture on the screen at different distances therefrom,the amount of light transmitted through one lens when located at adistance from the screen to produce a certain size picture beinapproxlmately the same as the amount 0 light transmitted through anotherlens situated at a correspondingly difi'erent distance from the screenand producing the same size picture as the first lens. An operator musttherefore be provided with several different lenses in order to producea picture on the screen of a certain size if under difi'eringcircumstances it becomes necessary to situate the projection apparatusat a greater or less distance from the screen.

With the present invention, therays of light leaving the lens in thedirection toward the screen may be expanded or compacted to produce alarger or smaller picture as desired without the necessity of moving theprojection apparatus, or the same size picture may be produced atvarying distances from the screen.

The invention will be best understood from a consideration of thefollowing detail description taken in connection with the accompanyingdrawings forming a part of this specification, in which drawings,

Figure l is a perspective View of the attachment as applied to aprojection lens. Fi 2 is a section on the line AB of Fig. l.

fieferring to the drawings there is shown a projection lens 1 which maybe considered as attached to the front board 2 of a projection apparatuswhich latter may also be considered as of the motion picture typealthough the invention is not confined to a motion picture projectionmachine but may be used in connection with a stereopticon or with otherlenses than projection lenses.

There is provided a clip 3 in the form of a clamp band adapted toencircle the barrel of the lens 1 and this band may be made of a singlestrip bent into circular form and having the meeting ends bent intoparallel relation as shown at 4, these ends being perforated for thepassage of the clamp bolt 5 carrying a nut 5 which may be in the form ofa thumb or wing nut for ready manipula tion. The length of the band 3 issuch that when encircling the barrel of the lens 1 and the clamp nut 5is tightened the ends 4 are brought into close relation and thereby theband 3 is firmly clamped to the barrel of the lens 1.

The clamp band 3 is formed with or has attached to it strips 6, 7 and 8,the strips 6 and 7 being in parallel relation and attached to or formedon the band 3 at diametrically opposite points thereon. The strip 8projects in the same direction as the strips 6 and 7 but is displaced 90from each. Of course other relations of these strips may be provided.

Mounted on the strip 8 is a slide 9 provided with a handle 10 projectingin a direction away from the strips 6 and 7. These strips 6 and 7 eachcarry a respective slide 1l-12 and the three slides 9, ll, 12 areconnected by an annular band or ring 13. Secured in the ring 13 is alens 14 so related to the optical parts of the lens 1 that on beingmoved toward or from the said lens 1 the light rays passing through thelens 1 are caused to diverge or to approach in accordance with thedirection of movement of the lens 14 with relation to the lens 1 and sothe image produced on the screen is enlarged or contracted without thenecessity of moving the projection apparatus with relation to the screenupon which the picture is produced.

The arms or strips 6, 7 and 8 serve to guide the lens 14 in its movementto and from the lens 1.

It will be observed that the strips 6 and 7 are set on edge in verticalplanes while the strip 8 lies fiat in a horizontal plane. Any tendencytherefore of the strips 6 and 7 to bend horizontally is resisted by thestrip 8 which is wide in the direction of'such movement, while anytendency of the strip 8 to bend up or down is resisted by the strips 6and T which are on edge to resist movement in this direction. The threearms 6, 7 and 8 therefore together resist any movement of the lens 4 outof the optical axis of the lens 1. It will be observed that two arms orstrips 6 and 7 are used to the one arm 8. This is because of the weightof the lens 14: tending to bend the arm or strip 8 and this tendency ismore effectually resisted by having the two arms or stri 6 and 7,besides the three strips act as efficient guides permitting the easymovement of the lens ll without binding and yet without lost motion.

The operator may readily adjust the lens 14 with relation to the lens 1by grasping the handle 10 and moving the lens 14: to or from the lens 1as may be found necessary.

If the lens 1 be a one-quarter lens then by the use of the lens 14 thisone-quarter lens may be converted into a two-quarter or a three-quarteror a four-quarter lens while all intermediate points are also covered.

If it be necessary to place the projection apparatus close to the screenthen the light rays may be caused to expand thus producing upon thescreen an image of the desired size. If it be necessary to place theprojection apparatus farther away from the screen then the light conemay be contracted to adapt the image to the screen. Thus with a singleprojection lens 1 the same size image may be produced upon the screen atvarying distances of the projection apparatus from the screen, or largeror smaller images may be produced with theone projection lens with theprojection apparatus at/the sa distance from the screen.

' Projection lenses vary in price in accordance with the size and focallength, the larger size lenses being considerably more expensive thanthe smaller size. With the present invention the short focus lens andtherefore. a comparatively cheap lens may be made to take the place of acomplete battery of lenses, with the added advantage of having anindefinite number of intermediate adjustments not possible withprojection lenses as manufactured.

While the present invention has been described as applied to aprojection lens it will be understood that it is also applicable toother lenses and may operate in the reverse direction as for instance inthe case of a photographic lens, the lens 14 may be placed in front ofthe photographic lens so as to modify the image acting on thephotographic plate.

lVhat is claimed is 1. An attachment for lenses comprising a holdingmember adapted to be secured to a lens barrel, a carrier slidable on theholder, and a light modifying element mounted in the carrier in fixedrelation thereto, said carrier with the light modifying element thereinbeing adapted to be moved to and from the lens bodily in the opticalaxis of said lens to vary the size of the image produced by the lens.

2. An attachment for lenses comprising a clamp band adapted to encirclea lens barrel and having arms projectin therefrom parallel with theoptical axis of the lens, a carrier sustained by the arms and slidablelongitudinally thereon, and a lens mounted in said carrier.

8. An attachment for lenses comprising a clamp band adapted to encirclethe barrel of a lens and having arms projecting therefrom in spacedrelation one to the other and parallel with the optical axis of thelens, the arms coacting to resist bending out of parallelism with theoptical axis of the lens, another lens eoacting with the first namedlens to modify the light rays to a different extent than the first namedlens, and a carrier for the second named lens having sliding membersconnected together and on and movable along respective ones of the armscarried by the clamp band.

1. An attachment for lenses comprising a plurality of arms connectedtogether at one end and adapted to be applied to the barrel of a lens inparallel relation with the optical axis of the lens, and a sliding lenscarrier connecting and movable along said arms in the direction of thelength of the latter.

In testimony that I claim the foregoing as my own, I have hereto affixedmy signature in the presence of two witnesses.

FRANK ULRIO WILLIAMS.

W'itnesses i E. M. BRONSON, L. V. BARRETT.

